Method and apparatus for the recovery of volatile organic compounds and concentration thereof

Abstract

A gas recovery apparatus and method for reclaiming and concentrating volatile organic compounds from the effluent of a semiconductor manufacturing operation is described. Vacuum Swing Adsorption is used to treat effluent containing volatile organic compounds to reversibly capture and subsequently release the volatile organic compounds, followed by recycle and / or cogeneration of the captured volatile organic compounds.

Description

BACKGROUND [0001] The present invention relates to a method and apparatus for recovering and concentrating constituents, e.g. volatile organic compounds, of effluent streams from semiconductor manufacturing operations, for purification, reuse and / or cogeneration of power, while concurrently improving the efficiency of effluent stream abatement. DESCRIPTION OF THE RELATED ART [0002] Many semiconductor processes, including spin coating of photoresist materials and azeotropic drying of wafers with alcohols, produce quantities of volatile organic compounds (VOCs) including, but not limited to, isopropanol, ethylacetate, acetone, propylene glycol monomethyl ether acetate (PGMEA) and hexamethyldisilazane (HMDA). Typically, the concentration of VOCs emitted from a semiconductor manufacturing process range from about 20 ppm to about 200 ppm in an effluent flow at least 10,000 CFM. Because VOCs are detrimental to human health and the environment, stricter legislative controls regarding emiss...

AI Technical Summary

Problems solved by technology

As a result of increased controls, the capital costs of the semiconductor manufacturing process facility have increased, including energy costs to effect recovery and destruction of VOCs prior to emission of the effluent stream into the environment.

Removing VOCs from large volumes of effluent stream using commonly used techniques such as catalytic recuperative oxidation, regenerative thermal oxidation and rotary concentration with thermal oxidation can be economically burdensome.

Notably, because of fluctuations in the volume and composition of the effluent stream, catalytic oxidizers tend to be greatly oversized.

It has been reported that the cost of operating this type of device in a typical U.S. industrial plant easily adds 25% to the yearly energy bill.

Additionally, these oxidizers tend to have large footprints and are economically burdensome due to the complexity of the system.

Notably, it has been reported that at concentration levels less than 500 ppm or greater than 15,000 ppm, recovery of VOCs from effluent by TSA is not economically justifiable.

Concentrations of VOCs above 15,000 ppm are typically in the explosive range thus requiring the use of a hot inert carrier gas, while recovery of VOC concentrations below about 500 ppm is technologically infeasible and hence economically burdensome.

Disadvantages of the Munters Zeol technology include a sizeable footprint and a concentration ratio of only about 10:1.

As such, small amounts of VOCs remain in a large volume of effluent.

Disadvantages of this method include that the high costs of operation are merely shifted from electricity to fuel.

Additionally, when the amount of VOCs in the air varies over time, the system is largely uncontrollable.

It is apparent that the removal and destruction of VOCs from the effluent stream of a semiconductor manufacturing process remains an obstacle that adversely impacts the economics of conventional semiconductor manufacturing facilities.

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